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Description
The following paper discusses the validation of the TolTEC optical design along with a progress report regarding the design of the optical mounting system. Solidworks and Zemax were used in conjunction to model the proposed optics designs. The final optical design was selected through extensive CAD modeling and testing within the Large Millimeter Telescope receiver room. The TolTEC optics can be divided into two arrays, one comprised of the warm mirrors and the second, cryogenically-operated cold mirrors. To ensure structural stability and optical performance, the mechanical design of these systems places a heavy emphasis on rigidity. This is done using a variety of design techniques that restrict motion along the necessary degrees of freedom and maximize moment of inertia while minimizing weight. Work will resume on this project in the Fall 2017 semester.
ContributorsKelso, Rhys Partain (Author) / Mauskopf, Philip (Thesis director) / Groppi, Christopher (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Standard cosmological models predict that the first astrophysical sources formed from a Universe filled with neutral hydrogen (HI) around one hundred million years after the Big Bang. The transition into Cosmic Dawn (CD) that seeded all the structures seen today can only be probed directly by the 21-cm line of neutral hydrogen. Redshifted by the Hubble expansion, HI signal during CD is expected to be visible in radio frequencies. Precisely characterized and carefully calibrated low-frequency instruments are necessary to measure the predicted ~10-200 mK brightness temperature of this cosmological signal against foregrounds. This dissertation focuses on improving the existing instrumental and analysis techniques for the Experiment to Detect the Global EoR Signature (EDGES) and building capabilities for future space-based 21-cm instruments, including the Farside Array for Radio Science Investigations of the Dark ages and Exoplanets (FARSIDE) concept.Frequency-dependent antenna beams of 21-cm instruments limit the removal of bright galactic foreground emission (~10^3 - 10^4K) from observations. Using three electromagnetic simulation packages, I modeled the EDGES low-band antenna, including the ground plane and soil, and quantified its variations as a function of frequency. I compared simulated observations to sky data and obtained absolute agreement within 4% and qualitatively similar spectral structures.
I used the new open-source edges-analysis pipeline to carry out rigorous fits of the absorption feature on the same low-band data and lab calibration measurements as (Bowman et. al. 2018). Using a Bayesian framework, I tested a few calibration choices and found posteriors of the best-fit 21-cm model parameters well within the 1σ values reported in B18. To test for the ``global'' nature of the reported cosmic absorption feature, I performed a time-dependent analysis. Initial results from this analysis successfully retrieved physical estimates for the foregrounds and estimates of the cosmic signal consistent with previous findings.
The array layout of FARSIDE, a NASA probe-class concept to place a radio interferometer on the lunar farside, is a four-arm spiral configuration consisting of 128 dual-polarized antennas with a spatial offset between the phase centers of its orthogonal polarizations. I modeled the impact of direction-dependent beams and phase offsets on simulated observations of all four Stokes parameter images of a model and quantified its effects on the two primary science cases: 21-cm cosmology and exoplanet studies.
ContributorsMahesh, Nivedita (Author) / Bowman, Judd D (Thesis advisor) / Jacobs, Daniel C (Committee member) / Groppi, Christopher (Committee member) / Shkolnik, Evgenya (Committee member) / Windhorst, Rogier (Committee member) / Arizona State University (Publisher)
Created2022
Description
The work presented herein will present the methodology and results for characterizing the thermal and electrical characteristics of the high gain warm IF amplifiers being developed by Arizona State University (ASU) for the GUSTO radio astronomy instrument. Thermal analysis will be performed in the form of Thermal Desktop simulations, hand calculations, and lab measurements. The electrical characteristics of the LNA design are then examined by collecting S-parameter measurements of the entire GUSTO band across a temperature range of -40°C to +70°C. Ultimately, the work performed justifies that ASU’s design of the GUSTO electronics is capable of meeting all technical requirements necessary to achieve mission success.
ContributorsRogers, Sarah (Author) / Groppi, Christopher (Thesis director) / Mauskopf, Philip (Committee member) / Mani, Hamdi (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
TolTEC is a three-band millimeter-wave, imaging polarimeter installed on the 50 m diameter Large Millimeter Telescope (LMT) in Mexico. This camera simultaneously images the focal plane at three wavebands centered at 1.1 mm (270 GHz), 1.4 mm (214 GHz), and 2.0 mm (150 GHz). TolTEC combines polarization-sensitive kinetic inductance detectors (KIDs) with the LMT to produce high resolution images of the sky in both total intensity and polarization. I present an overview of the TolTEC camera’s optical system and my contributions to the optomechanical design and characterization of the instrument. As part of my work with TolTEC, I designed the mounting structures for the cold optics within the cryostat accounting for thermal contraction to ensure the silicon lenses do not fracture when cooled. I also designed the large warm optics that re-image the light from the telescope, requiring me to perform static and vibration analyses to ensure the mounts correctly supported the mirrors. I discuss the various methods used to align the optics and the cryostat in the telescope. I discuss the Zemax optical model of TolTEC and compare it with measurements of the instrument to help with characterization. Finally, I present the results of stacking galaxies on data from the Atacama Cosmology Telescope (ACT) to measure the Sunyaev-Zel’dovich (SZ) effect and estimate the thermal energy in the gas around high red-shift, quiescent galaxies as an example of science that could be done with TolTEC data. Since the camera combines high angular resolution with images at three wavelengths near distinct SZ features, TolTEC will provide precise measurements to learn more about these types of galaxies.
ContributorsLunde, Emily Louise (Author) / Mauskopf, Philip (Thesis advisor) / Groppi, Christopher (Committee member) / Scannapieco, Evan (Committee member) / Noble, Allison (Committee member) / Bryan, Sean (Committee member) / Arizona State University (Publisher)
Created2023